U.S. patent application number 13/263864 was filed with the patent office on 2012-02-09 for hydraulic circuit with multiple pumps.
Invention is credited to Dennis Reynolds, Amir Shenouda.
Application Number | 20120031087 13/263864 |
Document ID | / |
Family ID | 42342456 |
Filed Date | 2012-02-09 |
United States Patent
Application |
20120031087 |
Kind Code |
A1 |
Reynolds; Dennis ; et
al. |
February 9, 2012 |
HYDRAULIC CIRCUIT WITH MULTIPLE PUMPS
Abstract
A hydraulic circuit includes at least one actuator that may be
powered for performing a function. A plurality of valves are
associated with the at least one actuator for controlling a flow of
fluid into and out of the at least one actuator. The hydraulic
circuit also includes multiple pumps for supplying fluid to the at
least one actuator. The multiple pumps includes a first pump for
primarily powering the at least one actuator for movement in a
first direction and a second pump for primarily powering the at
least one actuator for movement in a second direction, opposite the
first direction.
Inventors: |
Reynolds; Dennis; (Fort
Wayne, IN) ; Shenouda; Amir; (Chicago, IL) |
Family ID: |
42342456 |
Appl. No.: |
13/263864 |
Filed: |
April 8, 2010 |
PCT Filed: |
April 8, 2010 |
PCT NO: |
PCT/US10/30335 |
371 Date: |
October 11, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61167618 |
Apr 8, 2009 |
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Current U.S.
Class: |
60/429 |
Current CPC
Class: |
F15B 2211/20576
20130101; F15B 11/0426 20130101 |
Class at
Publication: |
60/429 |
International
Class: |
F15B 11/08 20060101
F15B011/08 |
Claims
1. A hydraulic circuit comprising: at least one actuator that may
be powered for performing a function; a plurality of valves
associated with the at least one actuator for controlling a flow of
fluid into and out of the at least one actuator; multiple pumps for
supplying fluid to the at least one actuator, the multiple pumps
including a first pump for primarily powering the at least one
actuator for movement in a first direction and a second pump for
primarily powering the at least one actuator for movement in a
second direction, opposite the first direction.
2. The hydraulic circuit of claim 1 further including an electronic
controller for controlling the valves, the controller being
responsive to signals from an input device for controlling the
valves.
3. The hydraulic circuit of claim 2 wherein the first pump provides
fluid into a first supply conduit, the second pump provides fluid
into a second supply conduit, and a mixing valve is connected
between the first and second supply conduits, the mixing valve
being responsive to the controller for fluidly connecting the first
and second supply conduits.
4. The hydraulic circuit of claim 3 wherein the mixing valve is a
bi-directional pressure compensating valve that may be opened for
enabling the second pump to supplement the first pump for powering
movement the at least one actuator in the first direction and for
enabling the first pump to supplement the second pump for powering
movement the at least one actuator in the second direction.
5. The hydraulic circuit of claim 3 wherein the mixing valve is a
three-position valve that is biased into a neutral position
blocking flow between the first and second supply conduits, the
mixing valve adapted to be actuated into a first position for
enabling a flow of fluid from the first supply conduit to the
second supply conduit for enabling the first pump to supplement the
second pump for powering movement the at least one actuator in the
second direction and adapted to be actuated into a second position
for enabling a flow of fluid from the second supply conduit to the
first supply conduit for enabling the second pump to supplement the
first pump for powering movement the at least one actuator in the
first direction.
6. The hydraulic circuit of claim 3 further including a first
pressure sensor for sensing fluid pressure in the first supply
conduit and providing a first pressure signal to the controller, a
second pressure sensor for sensing fluid pressure in the second
supply conduit and providing a second pressure signal to the
controller, the controller being responsive to the first and second
pressure signals and signals from an input device for controlling
the first and second pumps and the mixing valve.
7. The hydraulic circuit of claim 2 further including a fluid power
storage sub-system having an accumulator and a valve for
controlling a flow of fluid out of the accumulator, the controller
controlling the valve of the fluid power storage sub-system for
powering the at least one actuator using fluid from the
accumulator.
8. The hydraulic circuit of claim 7 wherein the valve of the fluid
power storage sub-system further controls a flow of fluid into the
accumulator from the at least one actuator, the accumulator being
at least partially filled by the fluid received from the at least
one actuator.
9. The hydraulic circuit of claim 8 wherein the fluid power storage
sub-system further includes a charge pump for providing fluid to
the accumulator for filling the accumulator, a fluid conduit
between the charge pump and the accumulator including a check valve
for preventing fluid from flowing from the accumulator toward the
charge pump.
10. The hydraulic circuit of claim 2 wherein the plurality of
valves includes two supply side valves and two return side valves,
one of the supply side valves and one of the return side valves
generally being associated with movement of the at least one
actuator in the first direction, and the other one of the supply
side valves and the other one of the return side valves generally
being associated with movement of the at least one actuator in the
second direction.
11. The hydraulic circuit of claim 10 wherein one of the first and
second pumps is an overcenter pump that may be operated as a motor,
the controller being adapted to control the supply side valves so
as to direct fluid exiting the at least one actuator to the
overcenter pump operating as a motor, the overcenter pump operating
as a motor driving the other one of the first and second pumps.
12. The hydraulic circuit of claim 10 further including a
regeneration valve that enable the two supply side valves to be
fluidly connected, the regeneration valve being controlled by the
controller and opening to direct fluid exiting a chamber of the at
least one actuator that is reducing in volume into a chamber of the
at least one actuator that is increasing in volume.
13. The hydraulic circuit of claim 2 wherein the at least one
actuator includes a plurality of actuators, each one of the
plurality of actuators including two supply side valves and two
return side valves, one of the supply side valves and one of the
return side valves generally being associated with movement of the
actuator in the first direction, and the other one of the supply
side valves and the other one of the return side valves generally
being associated with movement of the actuator in the second
direction.
14. The hydraulic circuit of claim 13 further including a mixing
valve for connecting supply conduits associated with the first and
second pumps, the controller, in response to signals from an input
device commanding movement of a majority of the actuators in the
first direction and commanding movement of a minority of actuators
in the second direction, controlling the mixing valve to open to
enable the first pump to provide fluid for powering the movement of
all of the actuators when the first pump has sufficient capacity to
power the actuators as commanded.
15. The hydraulic circuit of claim 14 wherein the plurality of
actuators includes a linear actuator and a rotary actuator.
16. The hydraulic circuit of claim 13 wherein the first pump
provides fluid into a first supply conduit, the second pump
provides fluid into a second supply conduit, and a mixing valve is
connected between the first and second supply conduits, the mixing
valve being responsive to the controller for fluidly connecting the
first and second supply conduits and, wherein the controller is
responsive to signals from an input device for controlling movement
of the actuators, the controller, in response to signals from the
input device indicating a desire to move a majority of actuators in
the first direction and a minority of actuators in a second
direction, opening the mixing valve and attempting to supply fluid
for powering all of the actuators with the first pump.
Description
FIELD OF INVENTION
[0001] This invention is related to a hydraulic circuit and
particularly, to a hydraulic circuit having multiple pumps for
supplying fluid to an actuator.
BACKGROUND OF THE INVENTION
[0002] Some known hydraulic circuits, such as those commonly used
in mobile machinery, for example, excavators, include two pumps.
Since an excavator includes a minimum of four separate functions
(boom, arm, bucket, and swing), each pump acts as a primary source
for two of the functions. For example, in most excavator circuits,
a first pump acts as the primary hydraulic fluid source for the
swing and bucket functions and acts as a secondary hydraulic fluid
source for the boom function during raising operation; while a
second pump acts as the primary hydraulic fluid source for the boom
and arm functions and acts as a secondary hydraulic fluid source
for the bucket function. As a result of this design, during
operation of the excavator, both the first and second pumps often
operate at relatively low displacements. For example, during
actuation of only the swing and boom function, the first pump may
be operating at a 50% displacement for operating the swing, while
the second pump may be operating at a 30% displacement for
operating the boom. Generally, hydraulic pumps are quite
inefficient at partial displacements. As a result of these
inefficiencies, hydraulic circuits of the type described above can
be costly to operate.
SUMMARY OF THE INVENTION
[0003] According to the invention, a hydraulic circuit is provided
that includes at least one actuator that may be powered for
performing a function. A plurality of valves are associated with
the at least one actuator for controlling a flow of fluid into and
out of the at least one actuator. The hydraulic circuit also
includes multiple pumps for supplying fluid to the at least one
actuator. The multiple pumps includes a first pump for primarily
powering the at least one actuator for movement in a first
direction and a second pump for primarily powering the at least one
actuator for movement in a second direction, opposite the first
direction.
[0004] According to one embodiment, an electronic controller
controls the valves. The controller is responsive to signals from
an input device for controlling the valves.
[0005] According to an embodiment, the first pump provides fluid
into a first supply conduit and, the second pump provides fluid
into a second supply conduit. A mixing valve is connected between
the first and second supply conduits. The mixing valve is
responsive to the controller for fluidly connecting the first and
second supply conduits.
[0006] According to another embodiment, the hydraulic circuit
includes a fluid power storage sub-system having an accumulator and
a valve for controlling a flow of fluid out of the accumulator. The
controller controls the valve of the fluid power storage sub-system
for powering the at least one actuator using fluid from the
accumulator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 illustrates a hydraulic circuit constructed in
accordance with a first embodiment of the invention;
[0008] FIG. 2 illustrates a hydraulic circuit constructed in
accordance with another embodiment of the invention; and
[0009] FIG. 3 illustrates a hydraulic circuit constructed in
accordance with yet another embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0010] FIG. 1 illustrates a hydraulic circuit 10 constructed in
accordance with a first embodiment of the present invention. The
hydraulic circuit 10 includes an actuator 12 having a head side
chamber 14 and a rod side chamber 16. The head side chamber 14 and
the rod side chamber 16 are separated by a piston 13 of a
piston/rod assembly 15. The actuator 12 may be powered for
operating a function, shown generally by reference numeral 18. The
hydraulic circuit 10 also includes two hydraulic pumps 24 and 26.
In the embodiment illustrated in FIG. 1, the pumps 24 and 26 are
variable displacement pumps that may be actuated overcenter so as
to act like motors. The pumps 24 and 26 are controlled for
maintaining a substantially constant outlet pressure. In one
embodiment, the pumps 24 and 26 are axial piston pumps having a
movable swashplate, however, any type of hydraulic pumps capable of
varied displacement may be used. A power source 28 is connected to
the pumps 24 and 26 and is operable for driving the pumps. The
power source 28 may include a combustion engine, an electric motor,
or any other known source of motive power. During operation for
pumping fluid, pump 24 pulls fluid from a tank 30 and provides the
fluid into supply conduit 34. Likewise, during operation for
pumping fluid, pump 26 pulls fluid from the tank 30 and provides
the fluid into supply conduit 36.
[0011] The hydraulic circuit 10 of FIG. 1 also includes a plurality
of valves associated with the actuator 12 for controlling the flow
of fluid into and out of the actuator. The valves include two
supply side valves 40 and 42, and two return side valves 44 and 46.
In an alternative embodiment, the two return side valves may be
combined into a single three-position valve. The hydraulic circuit
10 may optionally include a mixing valve 48. As the hydraulic
circuit 10 of FIG. 1 includes only a single actuator 12, a single
mixing valve 48 is included in the circuit. When a hydraulic
circuit includes more than one actuator, one or more mixing valves
may be used. Supply side valve 40 is connected between and controls
the flow of fluid between supply conduit 34 and a conduit 54
leading to the head side chamber 14 of the actuator 12. Supply side
valve 42 is connected between and controls the flow of fluid
between supply conduit 36 and a conduit 56 leading to the rod side
chamber 18 of the actuator 12. Return valve 44 is connected between
and controls the flow of fluid between conduit 54 and a return
conduit 58. Similarly, return valve 46 is connected between and
controls the flow of fluid between conduit 56 and the return
conduit 58. The mixing valve 48 connects and controls the flow
between supply conduits 34 and 36.
[0012] FIG. 1 illustrates each valve 40, 42, 44, 46, and 48 as a
bi-directional pressure compensating valve. The valves, however,
can be any known type of valve including uni-directional valves.
The use of bi-directional valves for at least the supply valves 40
and 42 and the mixing valve 48, however, enables additional control
modes for the hydraulic circuit 10, as is discussed below.
[0013] FIG. 1 also illustrates an optional fluid power storage
sub-system 70. The fluid power storage sub-system 70 includes an
accumulator 72, an associated valve 74 and, optionally, a charge
pump 76. The charge pump 76 is operatively connected to the pumps
24 and 26 and the power source 28. FIG. 1 illustrates a common
shaft driving the pumps 24 and 26 and the charge pump 76. The
charge pump 76 is operable for pulling fluid from the tank 30 and
providing the fluid to the accumulator 72 via charge conduit 78 for
filling the accumulator. A check valve 80 located in charge conduit
78 prevents fluid from the accumulator 72 from flowing back through
the charge conduit 78 toward charge pump 76. The valve 74 connects
the accumulator 72 to conduit 54 and controls a flow of fluid out
of the accumulator. The valve 74 is a bi-directional valve for
enabling the accumulator 72 to provide fluid to the conduit 54 and
for enabling the conduit 54 to provide fluid to the accumulator
72.
[0014] The hydraulic circuit 10 also includes an electronic
controller 64. The controller 64 is operatively connected to and
controls the operation of the valves 40, 42, 44, 46, 48, and 74.
The controller 64 is response to input signals provided from an
operator input device 66 for controlling the valves 40, 42, 44, 48,
and 74 in a manner for operating the actuator as desired by an
operator. Each of the valves 40, 42, 44, 46, and 48 is responsive
to the control signals for opening and closing to control the flow
of fluid through the valve. The controller 64 also may control the
power source 28 or, alternatively, may communicate with another
controller that controls the power source 28. The pumps 24 and 26
also may be responsive to the control signals from the controller
64 for changing their displacement, such as by changing an angle of
their associated swashplates. Alternatively, the pumps 24 and 26
may be self-controlled to maintain a substantially constant
pressure at their outputs.
[0015] With reference again to the pumps 24 and 26, pump 24 is the
primary pump for supplying fluid for powering the actuator 12 for
movement in a first direction, while pump 26 is the primary pump
for supplying fluid for powering the actuator 12 for movement in a
second direction, opposite the first direction. FIG. 1 illustrates
pump 24 as the primary pump for providing fluid to the head side
chamber 14 of the actuator 12 and, illustrates pump 26 as the
primary pump for providing fluid to the rod side chamber 16 of the
actuator 12. If the demand of the actuator 12 is such that the
primary pump is insufficient for powering the actuator, the mixing
valve 48 may be opened and the other pump an this operation, the
secondary pump) may be used to supplement the flow of fluid
provided by the primary pump.
[0016] The hydraulic circuit 10 of FIG. 1 has a variety of control
modes. The controller 64 controls at least the valves 40, 42, 44,
46, 48, and 74 for controlling the flow of fluid through the
hydraulic circuit 10. The controller 64 controls the valves 40, 42,
44, 46, 48, and 74 and optionally, controls the pumps 24 and 26, in
a manner to provide the highest efficiency for the hydraulic
circuit 10 while performing as commanded by the input signals
received from operator input device 66.
[0017] To extend the actuator 12 of FIG. 1, fluid is provided to
the head side chamber 14 of the actuator 12. In response to a
pressure differential between the head side chamber 14 and the rod
side chamber 16 of the actuator 12, the piston/rod assembly 15
moves and fluid exits the rod side chamber 16 of the actuator.
Below are various control modes for extending the actuator 12 in
the hydraulic circuit 10 of FIG. 1. [0018] Operate the power source
28 to drive pump 24 while opening valve 40 to allow fluid to flow
from pump 24 through conduit 34, valve 40, and conduit 54 to the
head side chamber 14 of the actuator 12. Valve 46 is opened to
allow fluid exiting the rod side chamber 16 to flow to tank 30 via
conduit 56, valve 46, and conduit 58. [0019] Open valve 74 to allow
fluid to flow from the accumulator 72 through valve 74 and a
portion of conduit 54 to the head side chamber 14 of the actuator
12. Valve 46 is opened to allow fluid exiting the rod side chamber
16 to flow to tank 30 via conduit 56, valve 46, and conduit 58.
[0020] Open both valves 40 and 74 and operate to the pump 24 so
that the pump 24 and the accumulator 72 both provide fluid to the
head side chamber 14 of the actuator 12. Valve 46 is opened to
allow fluid exiting the rod side chamber 16 to flow to tank 30 via
conduit 56, valve 46, and conduit 58. This control mode is used
when pump 24 is insufficient to operate the actuator 12 as
commanded by the operator input device 66 and the accumulator 72 is
used to supplement the fluid flow from pump 24. [0021] In the event
that the flow from pump 24 and the accumulator 72 is insufficient
for powering the actuator 12 as commanded, valve 74 associated with
the accumulator 72 may be closed and the mixing valve 48 may be
opened so that pump 26 may be used to supplement (or augment) flow
to the head side chamber 14 of the actuator 12. Valve 46 is opened
to allow fluid exiting the rod side chamber 16 to flow to tank 30
via conduit 56, valve 46, and conduit 58. In this control mode,
pump 24 is the primary pump and pump 26 is a secondary pump that
supplements the flow of pump 24. Instead of both pumps 24 and 26
operating at partial displacement, pump 24 (the primary pump) is
operated at full displacement and additional flow is supplemented
by pump 26 (the secondary pump). The accumulator 72 may be used, as
necessary, for further supplementing the flow provided from pumps
24 and 26. [0022] To utilize the energy of the fluid exiting the
rod side chamber 16 of the actuator 12, valve 46 may be controlled
to remain closed and valve 42 may be opened to direct the flow to
pump 26, which is controlled (or actuated) overcenter so as to act
as a motor. Pump 26, acting as a motor, drives pump 24 (or aids the
power source 28 in driving pump 24) for providing fluid to the head
side chamber 14. The accumulator 72 may be used, as necessary, for
further supplementing the flow from pump 24. Additionally, charge
pump 76 is driven by pump 26 acting as a motor so that the
accumulator 72 may be charged during this control mode. [0023] In
another control mode, the flow of fluid exiting the rod side
chamber 16, after passing through valve 42, may be directed through
the mixing valve 48 to supply conduit 34 to supplement (or augment)
the flow from pump 24 as possible given the pressures in the supply
conduits 34 and 36.
[0024] To retract the actuator 12, fluid is provided to the rod
side chamber 16 of the actuator 12. In response to a pressure
differential between the rod side chamber 16 and the head side
chamber 14 of the actuator 12, the piston/rod assembly 15 moves and
fluid exits the head side chamber 14 of the actuator 12. Below are
various control modes for retracting the actuator 12 in the
hydraulic circuit of FIG. 1. [0025] Operate the power source 28 to
drive pump 26 while opening valve 42 to allow fluid to flow from
pump 26 through conduit 36, valve 42, and conduit 56 to the rod
side chamber 16 of the actuator 12. Valve 44 is opened to allow
fluid exiting the head side chamber 14 via conduit 54 to flow to
one or both of the tank 30 and, if valve 74 is opened, the
accumulator 72 to at least partially fill the accumulator. [0026]
In the event that the flow from pump 26 is not sufficient for
powering the actuator 12 as commanded, the mixing valve 48 may be
opened and pump 24 may be used to supplement (or augment) flow to
the rod side chamber 16 of the actuator 12. Valve 44 is opened to
allow fluid exiting the head side chamber 14 via conduit 54 to flow
to one or both of the tank 30 and, if valve 74 is opened, the
accumulator 72. In this control mode, pump 26 is the primary pump
and pump 24 is a secondary pump that supplements the flow of pump
26. Instead of both pumps 24 and 26 operating at partial
displacement, pump 26 (the primary pump) is operated at full
displacement and additional flow is supplemented by pump 24 (the
secondary pump). [0027] To utilize the energy of the fluid exiting
the head side chamber 14 of the actuator 12, valve 44 remains
closed and valve 40 is opened to direct the flow to pump 24, which
is controlled overcenter to act as a motor. Pump, 24 acting as a
motor, drives pump 26 (or aids in driving pump 26) for providing
fluid to the rod side chamber 16. [0028] In another mode, some of
the flow of fluid exiting the head side chamber 14, after passing
through valve 40, may be directed through the mixing valve 48 to
supply conduit 36 for regeneration back to the rod side chamber 16.
The remainder of the fluid exiting the head side chamber 14 is
directed to one of the accumulator 72 or the tank 30.
[0029] FIG. 2 illustrates a hydraulic circuit 100 constructed in
accordance with another embodiment of the invention. The hydraulic
circuit 100 includes multiple actuators. The actuators illustrated
in FIG. 2 include three linear actuators 102, 104, and 106 and one
rotary actuator 108; however, any type or combination of types or
actuators may be included in the hydraulic circuit 100. Actuator
102 includes a piston/rod assembly 110 that is movable for
actuating its associated function, shown generally by reference
numeral 112. The piston/rod assembly 110 separates a head side
chamber 114 and a rod side chamber 116 of the actuator 102.
Actuator 104 includes a piston/rod assembly 120 that is movable for
actuating its associated function, shown generally by reference
numeral 122. The piston/rod assembly 120 separates a head side
chamber 124 and a rod side chamber 126 of the actuator 104.
Similarly, actuator 106 includes a piston/rod assembly 130 that is
movable for actuating its associated function, shown generally by
reference numeral 132. The piston/rod assembly 130 separates a head
side chamber 134 and a rod side chamber 136 of the actuator 106.
Actuator 108 includes first and second ports 140 and 142,
respectively. Fluid entering the first port 140 tends to cause
clockwise rotation (or movement in a first direction) of a rotating
portion of the actuator 108. Fluid entering the second port 142
tends to cause counter-clockwise rotation (or movement in a second
direction) of a rotating portion of the actuator 108.
[0030] The hydraulic circuit 100 also includes two hydraulic pumps
150 and 152. The pumps 150 and 152 are variable displacement pumps
that may be actuated overcenter so as to act like motors. The pumps
150 and 152 are controlled for maintaining a substantially constant
outlet pressure. In one embodiment, the pumps 150 and 152 are axial
piston pumps having a movable swashplate, however, any type of
hydraulic pumps capable of varied displacement may be used. A power
source 154 is connected to the pumps 150 and 152 and is operable
for driving the pumps. During operation for pumping fluid, pump 150
pulls fluid from a tank 158 and provides fluid into supply conduit
160. Likewise, during operation for pumping fluid, pump 152 pulls
fluid from the tank 158 and provides fluid into supply conduit
162.
[0031] As can be seen with reference to FIG. 2, pump 150 is
connected via conduit 160 to one side of each actuator. FIG. 2
illustrates pump 150 connected to the head side chambers 114, 124,
and 134 of each of actuators 102, 104, and 106, respectively, and
to the first port 140 of actuator 108. Thus, in the example
illustrated in FIG. 2, pump 150 acts as a primary pump for
supplying fluid for powering actuators 102, 104, and 106 for
movement in an extending direction and for powering actuator 108
for clockwise rotation. In FIG. 2, pump 152 is connected via
conduit 162 to the rod side chamber 116, 126, and 136 of each of
actuators 102, 104, and 106 and to the second port 42 of actuator
108. Thus, in the example illustrated in FIG. 2, pump 152 acts as a
primary pump for supplying fluid for powering actuators 102, 104,
and 106 for movement in a retracting direction and for powering
actuator 108 for counter-clockwise rotation.
[0032] FIG. 2 also illustrates an optional mixing valve 170 for
fluidly connecting supply conduits 160 and 162. The mixing valve
170 illustrated in FIG. 2 is a three-position valve that is biased
into a neutral (closed) position. The mixing valve 170 may be
actuated to a first position for connecting flow from supply
conduit 160 to supply conduit 162 or, may be actuated to a second
position for connecting flow from supply conduit 162 to supply
conduit 160. Flow between the supply conduits 160 and 162 enables
the pumps 150 and 152 to combine flows, if necessary, so that one
pump may supplement the flow of the other pump as described with
reference to FIG. 1.
[0033] The hydraulic circuit 100 of FIG. 2 also includes a
plurality of valves for controlling the flow of fluid into and out
of each of the actuators 102, 104, 106, and 108. In FIG. 2, each
actuator 102, 104, 106, and 108 includes four valves. The four
valves include two supply side valves 180 and 182 and two return
side valves 184 and 186. In the illustrated embodiment, at least
the supply side valves 180 and 182 are bi-directional valves, such
as, for example, bi-directional pressure compensating valves
similar to those illustrated in FIG. 1. The return side valves 184
and 186 may be similar to the supply side valves 180 and 182 or
simply may be two-position uni-directional valves for either
blocking flow to tank 158 or enabling flow to tank 158.
Alternatively, the return side valves may be combined into a single
three-position valve.
[0034] FIG. 2 also illustrates two pressure sensors 190 and 192.
Pressure sensor 190 is adapted for sensing the pressure within
supply conduit 160 and for outputting a pressure signal indicative
of the sensed pressure. Similarly, pressure sensor 192 is adapted
for sensing the pressure within supply conduit 162 and for
outputting a pressure signal indicative of the sensed pressure.
[0035] The hydraulic circuit 100 of FIG. 2 also includes a
controller 200. The controller 200 receives signals from the
pressure sensors 190 and 192 and also receives signals from an
input device 202. The input device 202 may be, for example, a
joystick for receiving commands from an operator, in which case the
signals from the input device 202 are indicative of the operator
commanded actuation of the actuators 102, 104, 106, and 108. The
controller 200 is responsive to the input signals from the input
device 202 and the pressure signals from the pressure sensors 190
and 192 for controlling the pumps 150 and 152 and the valves 170,
180, 182, 184, and 186 of the hydraulic circuit 100 in a manner to
provide the highest efficiency while performing as commanded. The
controller 200 also may prioritize actuation of the various
actuators 102, 104, 106, and 108 and control the valves 170, 180,
182, 184, and 186 in a manner for providing priority to one or more
actuators. Various control modes for the hydraulic circuit 100 of
FIG. 2 are described below. These described control modes do not
provide priority to any of the actuators. From the description
provided, those skilled in the art should recognize how to control
the valves 170, 180, 182, 184, and 186 in a manner for providing
priority to one or more actuators.
[0036] To extend one or more of the actuators 102, 104, and 106
and/or cause clockwise rotation of actuator 108, the hydraulic
circuit 100 of FIG. 2 is controlled in one of the following control
modes: [0037] Operate the power source 154 to drive pump 150 while
opening the supply side valves 180 of the actuators 102, 104, 106,
and 108 to allow fluid to flow from conduit 160 to the appropriate
head side chamber 114, 124, 134, respectively, of the actuators
102, 104, and 106 to be extended and/or to the first port 40 of
rotary actuator 108. Appropriate return side valves 186 of the
actuators 102, 104, 106, and 108 are opened to allow fluid exiting
the actuators to flow to tank 158. [0038] In the event that the
flow from pump 150 is not sufficient for powering the actuators
102, 104, 106, and 108 as commanded, the mixing valve 170 is opened
and pump 152 is used as a secondary source to supplement (or
augment) fluid flow to the head side chambers of the actuators 102,
104, and 106 to be extended and/or to the first port 40 of the
rotary actuator 108. The controller 200 may make a determination
that pump 150 is not sufficient for powering actuators 102, 104,
106, and 108 by monitoring pressure sensor 190. Alternatively, if
supply side valve 180 is a pressure compensating valve, the
controller 200 may monitor a position of the compensator for
determining whether pump 150 is sufficient for powering actuators
102, 104, 106, and 108. As the compensator has a moving spool (or
poppet) that moves in response to changes in pressure, the position
of the spool (or poppet) is indicative of pressure. Thus, the
compensator acts as the pressure sensor. Appropriate return side
valves 186 of the actuators 102, 104, 106, and 108 are opened to
allow fluid exiting the actuators to flow to tank 158. [0039] To
utilize the energy of the fluid exiting the actuators 102, 104,
106, and 108, fluid is supplied to the actuators 102, 104, 106, and
108 as set forth above and the return side valves 186 are
controlled to the closed position. The supply side valves 182 are
opened to direct the fluid flow exiting the actuators to pump 152,
which is controlled overcenter to act as a motor. Pump 152, acting
as a motor, drives pump 150 (or aids in driving pump 150) for
providing fluid. [0040] In another mode, the flow of fluid exiting
the rod side chamber of the one or more actuators being extended,
for example, chamber 126 of actuator 104, may be directed through
the supply side valve 182 into conduit 162. The fluid may pass from
conduit 162 through the mixing valve 170 (when appropriately
positioned) and into conduit 160 to be directed into chamber 124 of
actuator 104, via supply side valve 180 as possible given pressures
in the conduits 160 and 162.
[0041] To retract one or more of the actuators 102, 104, and 106
and/or cause counter-clockwise rotation of actuator 108, the
hydraulic circuit 100 is controlled in one of the following control
modes: [0042] Operate the power source 154 to drive pump 152 while
opening the appropriate supply side valves 182 to actuators 102,
104, 106, and 108 to allow fluid to flow from conduit 162 to the
appropriate rod side chamber 116, 126, 136, respectively, of the
actuators 102, 104, and 106 to be retracted and/or to the second
port 42 of the rotary actuator 108. Appropriate return side valves
184 of the actuators 102, 104, 106, and 108 are opened to allow
fluid exiting the actuators to flow to tank 158. [0043] In the
event that the flow from pump 152 is not sufficient for powering
the actuators 102, 104, 106, and 108 as commanded, the mixing valve
170 is opened and pump 150 is used as a secondary source to
supplement (or augment) fluid flow to the rod side chambers of the
actuators 102, 104, and 106 to be retracted and/or the second port
42 of the rotary actuator 108. The controller 200 may make a
determination that pump 152 is not sufficient for powering
actuators 102, 104, 106, and 108 by monitoring pressure sensor 192.
Alternatively, if supply side valve 182 is a pressure compensating
valve, the controller 200 may monitor a position of the compensator
for determining whether pump 152 is sufficient for powering
actuators 102, 104, 106, and 108. Appropriate return side valves
184 of the actuators 102, 104, 106, and 108 are opened to allow
fluid exiting the actuators to flow to tank. [0044] To utilize the
energy of the fluid exiting the actuators 102, 104, 106, and 108,
fluid is supplied to the actuators 102, 104, 106, and 108 as set
forth above and the return side valves 184 are controlled to the
closed position. The supply side valves 180 are opened to direct
the fluid flow exiting the actuators to pump 150, which is
controlled overcenter to act as a motor. Pump 150, acting as a
motor, drives pump 152 (or aids in driving pump 152) for providing
fluid. [0045] In another mode, the flow of fluid exiting the head
side chamber of one or more actuators being retracted, for example,
chamber 124 of actuator 104, may be directed through the supply
side valve 180 into conduit 160. The fluid may pass from conduit
160 through the mixing valve 170 (when appropriately positioned)
and into conduit 162 to be directed into chamber 126 of actuator
104, via supply side valve 182 as possible given pressures in
conduits 160 and 162.
[0046] At times, it may be desirable to actuate a majority of the
actuators 102, 104, 106, and 108 in one direction and a minority of
the actuators in an opposite direction. For example, assume that
actuators 102 and 104 are commanded to extend, actuator 108 is
commanded to rotate clockwise, and actuator 106 is commanded to
retract. In such a scenario, pump 150, which based upon the
commanded actuation acts as the primary fluid source for the
majority of the actuators 102, 104, and 108, may be used for
powering all of the actuators, including actuator 106, if capable.
To power actuator 106 with fluid from pump 150, the controller 200
opens mixing valve 170 to enable fluid flow from supply conduit 160
into supply conduit 162 and valves 182 and 184 associated with
actuator 106 are opened for enabling fluid flow into chamber 136
and out of the chamber 134. In the event that pump 150 is incapable
of supplying sufficient fluid for actuating the actuators 102, 104,
106, and 108 as desired, the controller 200 will close the mixing
valve 170 and supply fluid for actuator 106 from pump 152.
[0047] FIG. 3 illustrates a hydraulic circuit 100A constructed in
accordance with yet another embodiment of the invention. Portions
of FIG. 3 that are similar to those described above with reference
to FIG. 2 use the same reference number as used in FIG. 2 with the
addition of the suffix "A" and are not described in detail with
reference to FIG. 3. The hydraulic circuit 100A of FIG. 3 includes
a fluid power storage sub-system 210 associated with actuator 102A.
Those skilled in the art should recognize that the other actuators
104A, 106A, and 108A may include a similar fluid power storage
sub-system or multiple actuators may share a common fluid power
storage sub-system. The fluid power storage sub-system 210 includes
an accumulator 212, an associated valve 214 and a charge pump 216
that is coupled to and driven by the power source 154A. When a
hydraulic circuit includes multiple fluid power storage sub-systems
a common charge pump may be used. The charge pump 216 is
operatively connected to the pumps 150A and 152A and the power
source 154A. The charge pump 216 is operable for pulling fluid from
the tank 158A and providing the fluid to the accumulator 212 via
conduit 220 for filling the accumulator. A check valve 222 located
in conduit 220 prevents fluid from the accumulator 212 from flowing
back through conduit 220 toward charge pump 216. The valve 214
connects the accumulator 212 to supply conduit 160A. The valve 214
is a bi-directional valve for enabling the accumulator 212 to
provide fluid to the supply conduit 160A and for enabling the
supply conduit 160A to provide fluid to the accumulator 212. Fluid
from the accumulator 212 may be used alone or in combination with
fluid from pump 150A (and supplemental pump 152) for extending
actuator 102A. The accumulator 212 may be charged by fluid provided
by the charge pump 216, by fluid exiting the head side chamber 114A
of the actuator 102A, by fluid provided by pump 150A, or by a
combination of the these devices.
[0048] FIG. 3 also illustrates two actuators 104A and 106A having
regeneration valves 230 that enable the supply side valves 180A and
182A to be fluidly connected. The regeneration valve 230
illustrated in FIG. 3 is merely representative and may be formed by
structures integral with the supply side valves 180A and 182A.
Those skilled in the art should recognize that any number of the
actuators may include regeneration valves 230. The regeneration
valves 230 direct fluid flowing out of a chamber with a volume that
is being reduced and into a chamber with a volume that is being
expanded. The control modes of the hydraulic circuit 100A in FIG. 3
are similar to those described with reference to FIG. 2 with the
addition of the use of the fluid power storage sub-system 210 for
actuator 102A, which is similar to that described with reference to
fluid power storage sub-system 70 in FIG. 1, and the use of the
regeneration valves 230 for actuators 104A and 106A.
[0049] Although the principles, embodiments and operation of the
present invention have been described in detail herein, this is not
to be construed as being limited to the particular illustrative
forms disclosed. They will thus become apparent to those skilled in
the art that various modifications of the embodiments herein can be
made without departing from the spirit or scope of the
invention.
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